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To address the problem of overcurrent caused by asymmetric short-circuit faults on the medium-voltage side of 220 kV transformers, this paper proposes a current-limiting scheme involving the installation of a fault current limiter (FCL) at the neutral point. A fault discrimination method based on neutral grounding current was developed. First, a simulation model was established to systematically compare the performance of three fault detection methods: the current instantaneous values (CIV), the rate of current changes (RCC), and the curvature of current waveform (CCW). The results indicated that the CCW offers the fastest fault discrimination response but posed a risk of missed detection when used alone. To enhance both the reliability and the speed of fault discrimination, a combined method using the CIV and the CCW was adopted, enabling fault discrimination within 2 ms. Finally, considering the harmonics and noise interference, a third-order Butterworth filter was introduced to reduce detection false. The findings provide theoretical and technical support for the rapid and reliable operation of transformer neutral-point FCLs.

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Neutral-Point Grounding Current Feature Selection and Fault Discrimination Under Asymmetrical Short-Circuits on the Medium-Voltage Side of a 220 kV Transformer

  • 会议论文

  • 发表日期：

    2026年

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  • Jun Zhao,
  • Chao Xing,
  • Zhigang Zhang,
  • Yuan Tian,
  • Shuguo Gao,
  • Bin Wei,
  • Weiqi Qin

摘要

To address the problem of overcurrent caused by asymmetric short-circuit faults on the medium-voltage side of 220 kV transformers, this paper proposes a current-limiting scheme involving the installation of a fault current limiter (FCL) at the neutral point. A fault discrimination method based on neutral grounding current was developed. First, a simulation model was established to systematically compare the performance of three fault detection methods: the current instantaneous values (CIV), the rate of current changes (RCC), and the curvature of current waveform (CCW). The results indicated that the CCW offers the fastest fault discrimination response but posed a risk of missed detection when used alone. To enhance both the reliability and the speed of fault discrimination, a combined method using the CIV and the CCW was adopted, enabling fault discrimination within 2 ms. Finally, considering the harmonics and noise interference, a third-order Butterworth filter was introduced to reduce detection false. The findings provide theoretical and technical support for the rapid and reliable operation of transformer neutral-point FCLs.